15min:
ELECTRONIC GAS PHASE SPECTRA OF LARGER POLYACETYLENE AND PROTONATED POLYACETYLENE CATIONS.

ANATOLY DZHONSON, EVAN B. JOCHNOWITZ, EUNSOOK KIM AND JOHN P. MAIER, Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland.

A new approach has been developed for the purpose of measuring electronic transitions to bound excited states for cations that have been collisionally relaxed to low vibrational and rotational temperatures ( sim25 K). This has been used to obtain the first gas phase spectra of three new polyacetylene cation chains (HC12H+, HC14H+, and HC16H+) as well as two different protonated species (HC6H2+ and HC8H2+) using a two-color ion-photodissociation approach applied to ions held in a 22-pole trap. Specifically, the origin bands of the A 2 Pi - X 2 Pi electronic transitions of HC12H+, HC14H+, and HC16H+ were located at 10811, 9333, and 8739 cm-1, respectively, while the B 1A1 - X 1A1 transitions of HC6H2+ and HC8H2+ ( C 2v geometry) were recorded at 26404.0 and 21399.8 cm-1.